The application of composts and manures to a field, and the seeding or planting of a crop in the field is historically done with several operations and passes over the field.
When applying composts and manures to a field in large scale farming operations, it is desirable to optimise the utilisation of the material resource (i.e. compost or manure), and to consolidate machinery operations.
It is highly desirable to extend the time that nutrients and moisture are available to plants. Making the moisture and nutrients available to plants for an extended period of time helps to make the plants more productive.
It is also desirable to stop the nutrients being mobile in the soil and leeching out into adjacent waterways.
It is also highly desirable to keep carbon in the ground and out of the atmosphere.
It is desirable to provide sanctuary to soil microbiology that will enable it to survive during extended dry periods (e.g. between cropping over summer). It is desirable to encourage the proliferation of beneficial soil microbiology.
In agriculture, hardpan is a general term for a dense layer of soil, usually found below the uppermost topsoil layer. There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer that is largely impervious to water. Some hardpans are formed by deposits in the soil that fuse and bind the soil particles. These deposits can range from dissolved silica to matrices formed from iron oxides and calcium carbonate. Others are man-made, such as hardpan formed by compaction from repeated ploughing and/or heavy traffic and pollution from man-made sources.
Hardpan can be a problem in farming by impeding drainage of water and restricting the growth of plant roots. In these situations, the hardpan can be broken-up by either mechanical means such as digging or ploughing, or through the use of soil amendments.
A problem with ploughing the hardpan to break it up is that the hardpan will tend to reform, particularly if, after being broken-up, the soil is again compacted from repeated ploughing etc.
Soil amendments can be employed to alter the soil structure and promote dissolution of the hardpan. It has been observed that increasing the amount of soil organic matter through the working-in of manure, compost, or peat can both improve local drainage and promote the proliferation of earth worms that can, over time, break relatively thin hardpan layers.
A problem with using soil amendments such as manure and compost to break-up hardpan is that the manure and compost can be difficult to work into the soil.
Soil cultivation at the hardpan level includes several obstacles, including compaction, as mentioned above, which acts to reduce the ability of the soil to absorb and retain moisture. Reducing the ability of the soil to absorb and retain moisture consequently results in a build-up of contaminants such as salts that plant roots cannot penetrate, and that can cause harm to plants.
Nutrients, salts and other contaminants resting on the hardpan are more likely to be dissolved and transported through the topsoil to contaminate other areas such as waterways. The leaching of salts and nutrients is a well documented source of pollution for waterways.
Deep ripping to beneath the hardpan over large areas to add soil amendments that assist to halt the leaching of nutrients and salts is expensive and time consuming. Without a soil amendment or proper management, the hardpan will reform.
Traditionally, the adding of soil amendments and the sowing of a crop involve several operations. Any means of limiting the amount of operations and optimising inputs is desirable for several reasons, including: lessening exposure of the soil to heavy machinery which can compact the soil and create hardpan; lessening the time, energy, and capital spent on cultivation operations; more efficient use of fertilisers; and retention of moisture in the subsoil.
Placement of soil amendments such as compost increases the percentage of organic material that is in the soil and that is able to retain nutrients and moisture.
Before they are placed in the soil, it is usually desirable to pelletise/concentrate/compress composts and manures to slow the release of nutrients from them and, in particular, to aid in the slowing of de-nitrification.
It is desirable to add charcoal to the compost or manure as these materials are complementary in their ability to provide sanctuary to living soil microbes and will enhance the ability of the compost/manure and the living microbes contained in the compost/manure to store carbon in the subsoil with the advantage of providing plant nutrients.
Traditionally, the pelletisation process takes place at a location that is remote from the field that is being cultivated, and additional transportation is required for delivery to the pelletising plant of the raw materials, including compost or manure, to be pelletised, and to deliver the pelletised material to the field.
The process of pressure pelletisation destroys any living organisms that are a desirable product of the composting process. Pelletisation also destroys the desirable structure of the charcoal particles that may be added to the compost or manure as part of the pelletising process.
Presently, several operations are involved in applying extruded or pelletised compost or manure to a field, and then planting or sowing the field. These operations include: transporting the raw materials from which the pellets are made to a processing plant for pelletisation; transporting the pelletised material to the field; spreading the pelletised material on the field; ploughing the pelletised material into the field; and sowing or planting the crop into the field, and simultaneously installing water drip irrigation tubes.
Apparatus for applying slurries/liquids into or onto the ground are known. Examples of such apparatus are disclosed by the following published patent documents: U.S. Pat. No. 4,232,616 (VAN DER LELY); EP 0,520,784 B1 (GREENTRAC LIMITED); U.S. Pat. No. 4,114,815 (GIJSBERS); WO 2006/133697 A1 (STOLBERG-ROHR); and GB 2,251,166 A (CAVANAGH et al.). All of the apparatus disclosed by these documents receive pre-processed material that is already in a liquid slurry form.
It is against this background that the present invention has been developed.